1. Field of the Invention
The present invention relates to a method for manufacturing a printed wiring board which includes a core substrate having a penetrating hole, a first conductive circuit and a second conductive circuit formed on the core substrate, and a through-hole conductor formed in the penetrating hole and connecting the first conductive circuit and the second conductive circuit.
2. Discussion of the Background
In Japanese Laid-Open Patent Publication No. 2006-41463, a first opening portion is formed by irradiating a laser from an upper-surface side (first-surface side) of a core substrate, and a second opening portion is also formed by irradiating a laser from a lower-surface side (second-surface side). A penetrating hole is formed with the first opening portion and the second opening portion. The first opening portion tapers toward the second surface, and the second opening portion tapers toward the first surface. Then, by filling plating in the penetrating hole, a through-hole conductor with a small diameter is formed that can connect the upper and lower surfaces of the core substrate. The contents of this publication are incorporated herein by reference in its entirety.